Repeaters are widely used in wireless communication systems in order to re-amplify electromagnetic signals between e.g. a base station and a user equipment (UE) connected to a radio access network. Repeaters receive, amplify and retransmit signals of a particular channel. Being amplified, the signal can propagate over longer distances or it provides better quality, i.e., better signal to noise and interference ratio than the original signal. Repeaters are also known as layer-1 relay.
In the wireless communication systems Long Term Evolution (LTE) Advanced both relays (both layer-2 and layer-3) and repeaters may be introduced. Repeaters are preferred by some, since they do not introduce delay and are considered less costly.
It is sometimes desired to control the repeater from other nodes, e.g. from the eNodeB being the base station in LTE. The control is desired for example to turn amplification on and off frequency selectively.
In the evolution of LTE, it is expected that a control channel is standardized to control the repeater according to nodeB scheduling, turning on and off the repeater possibly frequency selective.
A Time Division Duplex (TDD) repeater being controlled by a nodeB scheduler is described in US 2007/0015462. In this document the repeater is associated with functionality similar to that associated with the user terminal; and wherein the functionality is used to receive the communications schedule.
To introduce a control protocol for the repeater that supports all desired control and surveillance increases the complexity of the standard.
Even if a control channel is introduced in standard it will probably not include all the desired functionalities for all vendors. Big companies can probably get their solutions into the standard while smaller companies with less influence in Third Generation Partnership Project (3GPP) will not. 3GPP is the name given to a project within the Third Generation Partnership Project to improve the 3G Mobile System to cope with future technology evolutions.
Also, in the standardization, a focus on the scheduling will be highly prioritized. There are other operation and control messages that will not be included in the standard, at least not in the first releases.
A control protocol may further require higher layer (layer-2?) capabilities which increase the complexity and cost of the repeater. US 2007/0015462 does not describe how the communication link between the scheduling node and the repeater shall be realized.
US 2008/219203 depicts a tunneling system which is used to overcome deficiencies of legacy frame structure. In this document, a base station sends data to mobile subscribers via repeaters. The data is sent in a tunnel packet mode in a first tunnel domain through relay stations to a relay station at the boundary of the first tunnel domain. The boundary relay station then translates the data from tunnel packet mode to legacy frame format in order to cross the from a first tunnel domain into a second tunnel domain. After receiving the data a relay station in the second tunnel domain translates the data back to tunnel packet mode for tunneling via relay stations to the mobile subscriber. In this way tunneling can be achieved with distributed control where the legacy mode must be used to send data among different tunnel domains. US 2008/219203 discloses a method for controlling data to be sent from a base station via relay stations to mobile subscribers. The control data is used to identify if a data frame is a tunnel burst mode frame or a legacy frame, to see if the if a translation from a tunnel burst mode to a legacy mode is required.
US200/3179721 discloses repeater messages such as feedback from the repeater to the “master” and repeater configuration messages sent from the master to the repeater. The configuration relates to enable or disable specific repeater functions, set timing parameters, signal thresholds, etc, i.e. to control the repeater. The configuration message is transmitted from the master as broadcast message addressing all repeaters, an individual repeater or a specific type of repeaters.